have just bought a 1998 6n that has been sittting a while and it gets damp inside and mists the windows up,has it runing the other day for and hour with heater on full blast and all appeared to be fine,but now inside of screen wet...

have so far checked and found NO wet carpets or leaking sunroof (factory fit glass)

inside boot dry and has original front screen,

front door seals ( 5 door) has had a little bit of water on top of the door seals as you open the doors...

is this just a case of using and keeping it warm inside??

the main reason of dampness in most cars is Door/window seals,

take a look at all the seals for the car, inspecting carfull for cracks and minor holes. sealant or clear drying superglue is a good patch up job.

Just dont shut your doors until its dryed

If its that bad, it maybe a good idea to put a electric heater inside the car for a good hour or so. just park it as close as you can to your home, plug it in, shut your door, lock it, done, just be careful you dont make a polo fireball.